DOCSLIB.ORG

[email protected] Prof

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Wei@Physics.Utoronto.Ca Prof PHY 294 – QUANTUM AND THERMAL PHYSICS DEPARTMENT OF PHYSICS, UNIVERSITY OF TORONTO Winter 2016 This course will be taught as two consecutive sections: Quantum Physics (Jan 6 – Feb 24) and Thermal Physics (Feb 25 - Apr 8). The general course, tutorial and laboratory information is given on this page. The individual syllabi for the two sections are given on the following pages. COURSE WEBSITE All the course related information will be posted on the Portal. An optional discussion forum will be set up in Pizza where you can ask/answer any course related questions. INSTRUCTORS Prof. John Wei, Office: MP 081, Phone: 416 946 5943, E-mail: [email protected] Prof. Erich Poppitz, Office: MP1113A, Phone: 416 946 7546, E-mail: [email protected] COURSE COORDINATOR Dr. Xingxing Xing, Office: MP129D, Phone: 416 978 4540, Email: [email protected] Please contact the course coordinator for matters relating to course administration, such as grading and teaching assistants. LECTURES 3 hours/week, in BA1180 (Wednesdays) or MP202 (Thursdays and Fridays). The first lecture is on Wednesday, Jan 6. Section Wednesday Thursday Friday LEC0101 1 pm in BA1180 11 am in MP202 9 am in MP202 LEC0102 12 pm in BA1180 12 pm in MP202 ENQUIRIES General questions that refer to physics being discussed in the course should be posted to the course discussion forum in Piazza. We will generally provide feedback on these within 1-2 business days. Detailed physics questions should be asked in person before/after lectures or during instructor/TA office hours. Other questions (such as those about grades, tutorial or other administrative issues) should be directed to the course coordinator by email or in person. COURSE MARKING SCHEME 10 % Quizzes 20 % Laboratories 30 % Two Term Tests (each 75 minutes) 40 % Final Examination (2.5 hours) TESTS AND EXAM Term Test 1: Monday Feb 8, 9 – 10:15 am; EX300, EX310 Term Test 2: Thursday Mar 24, 9 – 10:15 am; EX100 Final Exam: TBA (time to be scheduled by Faculty during April exam period) TUTORIALS AND QUIZZES The first tutorial is on Wednesday, Jan 13. The 10 tutorials run from Jan 13 to Mar 30. Suggested problems, not to be handed in, will be posted on the Portal and announced in class. Strategies for solving them will be discussed in the tutorials and solutions will be posted. Four quizzes, based on past suggested problems, will be given during the lectures and will be graded by your tutor and handed back the following week. The schedule of the tutorials and quizzes are listed below. Week (Week of) Tutorial Notes 1 (Jan 4) Jan 6: First class. No tutorial. 2 (Jan 11) 1 Jan 13: First tutorial. Jan 15: ESEC, no classes. 3 (Jan 18) 2 4 (Jan 25) 3 Jan 29: Quiz 1 (Quantum Physics). 5 (Feb 1) 4 6 (Feb 8) Feb 8: Term Test 1 (Quantum Physics); no tutorial. 7 (Feb 15) Reading week, no classes. 8 (Feb 22) Feb 25: Thermal Physics Part starts; special on Feb 5 26: Quiz 2 (Quantum Physics). 9 (Feb 29) 6 10 (Mar 7) 7 11 (Mar 14) 8 Mar 18: Quiz 3 (Thermal Physics). 12 (Mar 21) 9 Mar 24: Term Test 2 (Thermal Physics). 13 (Mar 28) 10 14 (April 4) Apr 8: Quiz 4 (Thermal Physics); last lecture. Group Day Time Room TA (Office, phone, email) TUT0101 Wed 5-6 pm HA401 Zaheen Sadeq (MP1026, 416-978-6185, [email protected]) TUT0102 Wed 5-6 pm WB242 Yige Chen (MP1005, 416-978-5208, [email protected]) TUT0103 Wed 5-6 pm SF2202 Paul Godin (MP704, 416-946-7129, [email protected]) TUT0104 Wed 5-6 pm WB144 Andrei Vovk (MP410, 416-978-8944, [email protected]) TUT0105 Wed 9-10 am BA2139 Zaheen Sadeq (MP1026, 416-978-6185, [email protected]) TUT0106 Wed 9-10 am BA2185 Yige Chen (MP1005, 416-978-5208, [email protected]) TUT0107 Wed 9-10 am BA2175 Paul Godin (MP704, 416-946-7129, [email protected]) TUT0108 Wed 9-10 am BAB024 Andrei Vovk (MP410, 416-978-8944, [email protected]) LABORATORIES The Lab Instructor for this course is Dr. Natalia Krasnopolskaia (Office: MP251A, 416-978-8803, [email protected]). LABORATORIES WEBSITE More information about the lab can be found on http://www.physics.utoronto.ca/~phy294lab/phy294lab.htm or the Portal. The lab is scheduled once every two weeks on Wednesdays with starting dates indicated below: Section Start Date Time Room PRA0101 2016/01/20 9 am – noon MP222 PRA0102 2015/01/13 9 am – noon MP222 PRA0103 2015/01/20 2 pm - 5 pm MP222 PRA0104 2015/01/13 2 pm - 5 pm MP222 PLEASE NOTE: the labs are booked and scheduled by you. As such, they do not necessarily follow the order of the content of the lectures and tutorials, and they may cover some PHY294 topics. QUANTUM PHYSICS SECTION LECTURER: Prof. John Wei Office / Phone: Room MP 081 / 416-946-5943 E-mail: [email protected] Office hours: by appointment Website: http://www.physics.utoronto.ca/~wei/ TEXTBOOK: Modern Physics (2nd edition), Randy Harris (Pearson Addison-Wesley). ADDITIONAL REFERENCES: 1) An Introduction to Quantum Physics, A.P. French & Edwin F. Taylor 2) Quantum Physics (3rd edition), S. Gasiorowicz 3) The Feynman Lectures on Physics, Volume III, Feynman-Leyton-Sands (free online at http://www.feynmanlectures.caltech.edu) These additional references have been placed on reserve in the physics library. TENTATIVE COURSE OUTLINE: For each lecture listed below, the corresponding sections in the textbook are given. For topics not covered in detail by the textbook, supplemental materials will be posted on Portal. 1. Review of wave-particle duality [§3.1 - 4.2] 2. Schrödinger equation & its implications [§4.3 - 4.7] 3. Stationary states in bound 1D systems [§5.1 - 5.5] 4. Finite square well & simple harmonic oscillator [§5.6 - 5.7] 5. Expectation values, operators & observables [§5.8 - 5.11] 6. Superposition of states in bound 1D systems [§5.9] 7. Unbound systems: steady-state approach [§6.1] 8. Potential steps and barriers [§6.1 - 6.2] 9. Quantum tunneling [§6.2 - 6.3] 10. Particle-wave propagation [§6.4] 11. 3D infinite square well [§7.1–7.2] 12. Schrödinger equation for a central force [§7.4-7.5] 13. The hydrogen atom [§7.6-7.8] 14. Spin: the Stern-Gerlach experiment [§8.1] 15. Two identical particles in a box [§8.2] 16. Pauli exclusion principle [§8.3] THERMAL PHYSICS SECTION LECTURER: Prof. Erich Poppitz Office / Phone: MP1113A / 416-946-7546 E-mail: [email protected] Office hours: by appointment Website: http://www.physics.utoronto.ca/~poppitz/ TEXTBOOK: An Introduction to Thermal Physics, Daniel Schroeder (Pearson Addison-Wesley). TENTATIVE COURSE SCHEDULE: 1. Th. Feb. 25: What is this class about? The ubiquity of microscopic and macroscopic systems and the need for different tools to describe them. The notion of thermal equilibrium and the ``zero-th law" of thermodynamics. 2. Fri. Feb. 26: Quiz II, Quantum 3. W. Mar. 2: The ideal gas. A classical microscopic model of the ideal gas, equipartition of energy, and its conservation. The first law of thermodynamics. 4. Th. Mar. 3: Heat and work. Classifying processes as quasistatic and non-quasistatic, adiabatic, isothermal, isobaric, etc. The corresponding processes for the ideal gas. 5. Fri. Mar. 4: Heat capacity at fixed volume or fixed pressure. Equipartition and the heat capacity of diatomic gases---the first puzzle that classical physics failed to explain. 6. W. Mar. 9: Reversible and irreversible processes. The tendency to maximize randomness and the usefulness of the statistical description. Micro- and macro- states, their multiplicities, their probabilities and the main postulate of statistitcal mechanics. 7. Th. Mar. 10: Entropy and the second law of thermodynamics. The spin paramagnet and the ideal gas. 8. Fri. Mar. 11: The entropy of the ideal gas, the Gibbs paradox and indistinguishability. 9. W. Mar. 16: The statistical notion of temperature. Thermal, mechanical, and diffusive equilibrium and the statistical definition of pressure and chemical potential. 10. Th. Mar. 17: Thermodynamic stability, inhomogeneous systems (the atmosphere!), metastable states and negative temperature. 11. Fri. Mar. 18: Quiz III, Thermal 12. W. Mar. 23: The use of heat and work in engines and refrigerators. The Carnot and other heat engines. Ideas behind magnetic and laser cooling. 13. Th. Mar. 24: Systems in contact with a ``reservoir," the Boltzmann distribution, the Helmholtz free energy, and the partition function. 14. W. Mar. 30: Partition function for a simple harmonic oscillator and how quantum statistics explains the jumps of the heat capacity. The partition function for the ideal gas. 15. Th. Mar. 31: The Maxwell velocity distribution. The chemical potential, the Saha equation and its application to chemistry, astrophysics and the Big Bang. 16. Fri. Apr. 1: Quantum ideal gases of indistinguishable particles. The Bose and Fermi distributions and ideas of their applications. 17. W. Apr. 6: The ultraviolet catastrophe and the blackbody radiation. The Cosmic Microwave Background as the perfect blackbody and the puzzles it raises. 18. Th. Apr. 7: Synthesis: review of what we covered and the (many) things left for the future. 19. Fri. Apr. 8: Quiz IV, Thermal Notice that I did not give chapters from the book that correspond to each topic as these are easy to match. It is clear that we cannot cover all topics from the book (but you are welcome to do so on your own) and that the schedule may have to be modified, most likely by dropping some examples if time pressures us. .
Load more

Recommended publications
  • Blackbody Radiation: (Vibrational Energies of Atoms in Solid Produce BB Radiation)
    Independent study in physics The Thermodynamic Interaction of Light with Matter Mirna Alhanash Project in Physics Uppsala University Contents Abstract ................................................................................................................................................................................ 3 Introduction ......................................................................................................................................................................... 3 Blackbody Radiation: (vibrational energies of atoms in solid produce BB radiation) .................................... 4 Stefan-Boltzmann .............................................................................................................................................................. 6 Wien displacement law..................................................................................................................................................... 7 Photoelectric effect ......................................................................................................................................................... 12 Frequency dependence/Atom model & electron excitation .................................................................................. 12 Why we see colours ....................................................................................................................................................... 14 Optical properties of materials: ..................................................................................................................................
    [Show full text]
  • 151545957.Pdf
    Universit´ede Montr´eal Towards a Philosophical Reconstruction of the Dialogue between Modern Physics and Advaita Ved¯anta: An Inquiry into the Concepts of ¯ak¯a´sa, Vacuum and Reality par Jonathan Duquette Facult´ede th´eologie et de sciences des religions Th`ese pr´esent´ee `ala Facult´edes ´etudes sup´erieures en vue de l’obtention du grade de Philosophiae Doctor (Ph.D.) en sciences des religions Septembre 2010 c Jonathan Duquette, 2010 Universit´ede Montr´eal Facult´edes ´etudes sup´erieures et postdoctorales Cette th`ese intitul´ee: Towards A Philosophical Reconstruction of the Dialogue between Modern Physics and Advaita Ved¯anta: An Inquiry into the Concepts of ¯ak¯a´sa, Vacuum and Reality pr´esent´ee par: Jonathan Duquette a ´et´e´evalu´ee par un jury compos´edes personnes suivantes: Patrice Brodeur, pr´esident-rapporteur Trichur S. Rukmani, directrice de recherche Normand Mousseau, codirecteur de recherche Solange Lefebvre, membre du jury Varadaraja Raman, examinateur externe Karine Bates, repr´esentante du doyen de la FESP ii Abstract Toward the end of the 19th century, the Hindu monk and reformer Swami Vivekananda claimed that modern science was inevitably converging towards Advaita Ved¯anta, an important philosophico-religious system in Hinduism. In the decades that followed, in the midst of the revolution occasioned by the emergence of Einstein’s relativity and quantum physics, a growing number of authors claimed to discover striking “par- allels” between Advaita Ved¯anta and modern physics. Such claims of convergence have continued to the present day, especially in relation to quantum physics. In this dissertation, an attempt is made to critically examine such claims by engaging a de- tailed comparative analysis of two concepts: ¯ak¯a´sa in Advaita Ved¯anta and vacuum in quantum physics.
    [Show full text]
  • Kelvin's Clouds
    Kelvin’s clouds Oliver Passon∗ July 1, 2021 Abstract In 1900 Lord Kelvin identified two problems for 19th century physics, two“clouds” as he puts it: the relative motion of the ether with respect to massive objects, and Maxwell-Boltzmann’s theorem on the equipartition of energy. These issues were eventually solved by the theory of special relativity and by quantum mechanics. In modern quotations, the content of Kelvin’s lecture is almost always distorted and misrepresented. For example, it is commonly claimed that Kelvin was concerned about the UV- catastrophe of the Rayleigh-Jeans law, while his lecture actually makes no reference at all to blackbody radiation. I rectify these mistakes and explore reasons for their occurrence. 1 Introduction In 1900, Lord Kelvin, born as William Thomson, delivered a lecture in which he identified two problems for physics at the turn of the 20th century: the question of the existence of ether and the equipartition theorem. The solution for these two clouds was eventually achieved by the theory of special relativity and by quantum mechanics [1]. Understandably, these prophetic remarks are often quoted in popular science books or in the introductory sections of textbooks on modern physics. A typical example is found in the textbook by Tipler and Llewellyn [2]: [...] as there were already vexing cracks in the foundation of what we now refer to as classical physics. Two of these were described by Lord Kelvin, in his famous Baltimore Lectures in 1900, as the “two clouds” on the horizon of twentieth-century physics: the failure of arXiv:2106.16033v1 [physics.hist-ph] 30 Jun 2021 theory to account for the radiation spectrum emitted by a blackbody and the inexplicable results of the Michelson-Morley experiment.
    [Show full text]
  • Note-A-Rific: Blackbody Radiation
    Note-A-Rific: Blackbody Radiation What is Blackbody How to Calculate Peak Failure of Classical Radiation Wavelength Physics What is Blackbody Radiation? As thermal energy is added to an object to heat it up, the object will emit radiation at various wavelengths. • All objects emit radiation at an intensity equal to its temperature (in degrees Kelvin, see Glossary) to the fourth power. 4 Intensity = T o At room temperatures, we are not aware of objects emitting radiation because it’s at such a low intensity. o At higher temperatures there is enough infrared radiation that we can feel it. o At still higher temperatures (about 1000K) we can actually see the object glowing red o At temperatures above 2000K, objects glow yellowish or white hot. No real object will absorb all radiation falling on it, nor will it re-emit all of the energy it absorbs. • Instead physicists came up with a theoretical model called a Blackbody. • A blackbody absorbs all radiation falling on it, and then releases all that energy as radiation in the form of EM waves. • As the temperature of a blackbody increases, it will emit more and more intense radiation. • At the same time, as the temperature increases, most of the radiation is released at higher and higher frequencies (lower and lower wavelengths). • The frequency at which the emitted radiation is at the highest intensity is called the peak frequency or (more typically) the peak wavelength. • This explains why an object at room temperature does not emit much radiation, and what radiation it does emit is at higher wavelengths, like infrared.
    [Show full text]
  • Blackbody Radiation and the Quantization of Energy
    Blackbody Radiation and the Quantization of Energy Energy quantization, the noncontinuous nature of energy,was discovered from observing radiant energy from blackb o dies. A blackbody absorbs electromagnetic EM energy eciently. An ideal blackb o dy absorbs all electromagnetic energy that b ears up on it. Ecient absorb ers of energy also are ecient emitters or else they would heat up without limit. Energy radiated from blackb o dies was studied b ecause the characteristics of the radiation are indep endent of the material constitution of the blackb o dy. Therefore, conclusions reached by the study of energy radiated from blackb o dies do not require quali cations related to the material studied. If you heat up a go o d absorb er emitter of EM energy, it will radiate energy with total p ower p er unit area prop ortional to the fourth p ower of temp erature in degrees Kelvin. This is the Stefan - Boltzmann law: 4 R = T ; 8 2 4 where the Stefan constant =5:6703 10 W/m K . This lawwas rst prop osed by Josef Stefan in 1879 and studied theoretically by Boltzmann a few years later, so it is named after b oth of them. The EM energy emitted from a blackb o dy actually dep ends strongly on the wavelength, , of the energy. Thus, radiantpower is a function of wavelength, R , and total p ower p er unit area is simply an integral over all wavelengths: Z R = R d: 1 The function R is called the blackbody spectrum. Recall that ! 2 c = f = ! =2f k = k The blackb o dy sp ectrum is di erent for di erent temp eratures, but has the same general shap e as the solid lines in Figure 1 show.
    [Show full text]
  • Blackbody Radiation and the Ultraviolet Catastrophe Introduction
    Activity – Blackbody Radiation and the Ultraviolet Catastrophe Introduction: A blackbody is a term used to describe the light given by an object that only gives off emitted light, in other words it doesn’t reflect light. Of course, in order for such an object to emit light it must get hot. In this activity, you are going to observe the nature of light given off by hot objects and determine if there is an empirical relationship between an object’s temperature and the light emitted. These are some helpful video links which provide an excellent foundation of knowledge of Blackbody Radiation. Crash Course (First Half of Video) https://www.youtube.com/watch?v=7kb1VT0J3DE&list=PL8dPuuaLjXtN0ge7yDk_UA0ldZJdhwkoV&index=44&t=438 s Professor Dave’s Summary on Blackbody Radiation and the Ultraviolet Catastrophe https://www.youtube.com/watch?v=7BXvc9W97iU PHET’s Manipulative Graph of Spectral Power Density vs. Wavelength https://phet.colorado.edu/en/simulation/blackbody-spectrum Draw a graph depicting classical blackbody radiation, (Y-axis is Spectral Power Density, X-axis is Wavelength). Complete the graph correlating the spectral power density to wavelength for the sun, as demonstrated on the Phet activity. Describe the correlation between wavelength of light emitted with the average kinetic energy of particles within a substance. Temperature in Kelvin for Red Light: Temperature in Kelvin for Yellow Light: Temperature in Kelvin for Violet Light: Questions: Dianna Cowern with PBS has an enthusiastic video explaining the origin of quantum topics. https://www.youtube.com/watch?v=FXfrncRey-4 What does the ultraviolet catastrophe refer to, and why does the curve collapse on the left-hand side of the graph? (At what approximate wavelength does the curve drop)? What is Max Planck’s explanation for the ultraviolet catastrophe, and how does it lead to the Planck equation? (Provide Planck equation and Planck’s constant).
    [Show full text]
  • Blackbody Radiation
    5. Light-matter interactions: Blackbody radiation The electromagnetic spectrum Sources of light Boltzmann's Law Blackbody radiation The cosmic microwave background The electromagnetic spectrum All of these are electromagnetic waves. The amazing diversity is a result of the fact that the interaction of radiation with matter depends on the frequency of the wave. The boundaries between regions are a bit arbitrary… Sources of light Accelerating charges emit light Linearly accelerating charge http://www.cco.caltech.edu/~phys1/java/phys1/MovingCharge/MovingCharge.html Vibrating electrons or nuclei of an atom or molecule Synchrotron radiation—light emitted by charged particles whose motion is deflected by a DC magnetic field Bremsstrahlung ("Braking radiation")—light emitted when charged particles collide with other charged particles The vast majority of light in the universe comes from molecular motions. Core (tightly bound) electrons vibrate in their motion around nuclei ~ 1018 -1020 cycles per second. Valence (not so tightly bound) electrons vibrate in their motion around nuclei ~ 1014 -1017 cycles per second. Nuclei in molecules vibrate with respect to each other ~ 1011 -1013 cycles per second. Molecules rotate ~ 109 -1010 cycles per second. One interesting source of x-rays Sticky tape emits x-rays when you unpeel it. Scotch tape generates enough x-rays to take an image of the bones in your finger. This phenomenon, known as ‘mechanoluminescence,’ was discovered in 2008. For more information and a video describing this: http://www.nature.com/nature/videoarchive/x-rays/
    [Show full text]
  • Undergraduate Course Handbook
    Undergraduate Course Handbook 2016-2017 Undergraduate Laboratory Images Images Laboratory Undergraduate The Course 1 These notes have been produced by the Department of Physics, University of Oxford. The information in this handbook is for the academic year Michaelmas Term 2016, Hilary Term 2017 and Trinity Term 2017. B A N B U Clarendon Laboratory R Y Lindemann and Martin Denys Wilkinson Building N R Wood lecture theatres Dennis Sciama lecture theatre O (via the Level 4 entrance) A D D Robert Hooke Building O A E R B L Teaching Faculty Office K E B L P A A C R K K H S Physics Teaching Laboratories S A T L (entrance down the steps) L R O GIL R D D A R D E M E U S U S ’ M gt The Department is able to make provision for students with special needs. If you think you may need any special requirements, it would be very helpful to us if you could contact the Assistant Head of Teaching (Academic) about these as soon as possible. Students in wheelchairs or with mobility needs can access the Lindemann and the Dennis Sciama Lecture Theatres by lifts from the ground floors. The Denys Wilkinson Building and the Clarendon Laboratory have toilet facilities for wheelchair users. The Martin Wood Lecture Theatre has access for wheelchairs and a reserved area within the theatre. There are induction loop systems for students with hearing difficulties in the Lindemann, Dennis Sciama and Martin Wood Lecture Theatres. Other provisions for students with special needs can be also be made.
    [Show full text]
  • Lecture 4 Introduction to Quantum Mechanical Way of Thinking
    Lecture 4 Introduction to Quantum Mechanical Way of Thinking. Today’s Program 1. Brief history of quantum mechanics (QM). 2. Wavefunctions in QM (First postulate) 3. Schrodinger’s Equation Questions you should be able to answer by the end of today’s lecture: 1. When do you observe wave-particle duality? 2. How to determine particle’s wavelength if you know its momentum? 3. What does the wavefunction represent? 4. How does wavefunction evolve in time? References for Today’s lecture: 1. Introductory Applied Quantum and Statistical Mechanics, Hagelstein, Senturia, Orlando. 2. Introduction to Quantum Mechanics, Griffiths. 1 In the end of 19th century and beginning of the 20th century, scientists were convinced they understood physics. Only a “handful” of experiments remained unexplained. These experiments became a foundation for the new kind of physics, which we now know as Quantum Mechanics. Today a lot of devices (all electronics, all optics) surrounding us are fundamentally quantum mechanical in their design and principles of operation. 1887, Hertz: Photoelectric effect. When illuminated with ultraviolet (UV) light metallic sample emitted electrons. However, the lower frequency (higher wavelength) light did not initiate electron emission even at higher incident light powers. ν I e I ν ν o Black Body Spectrum: The physicists were puzzled by the radiation of a black body, as it could not be explained by the Maxwell’s equations. Blackbody curves for various temperatures and comparison with classical theory. (This image is in the public domain. Source: Wikimedia Commons.) For short wavelength (high frequency) limit Wien’s law provided an approximation: const 1 P ,T ~ e T 5 const 3 T P,T ~ e For long wavelength (low frequency) Rayleigh-Jeans law provided another approximation: 2 T P ,T ~ Const 4 2 P,T ~ Const T Which, if correct, would have resulted in rapid increase of power at short wavelength (high frequency) labeled as “ultraviolet catastrophe”.
    [Show full text]
  • Ultraviolet Catastrophe”
    Chapter 2: The blackbody spectrum and the \ultraviolet catastrophe" Luis M. Molina Departamento de F´ısicaTe´orica,At´omicay Optica´ Quantum Physics Luis M. Molina (FTAO) Chapter 2: The blackbody spectrumQuantum and Physics the \ultraviolet 1 / 13 catastrophe" Thermal radiation What is thermal radiation? Thermal radiation is the electromagnetic radiation emitted by a body as a result of its temperature. All bodies emit such radiation to their surroundings and absorb such radiation from them. Usually, most of the radiation is emitted in frequencies outside the visible range. (for example, at the infrared at room temperature) All bodies (solids and liquids) emit a continuous spectrum of radiation. 1 Practically independent of composition 2 Strongly dependent on the temperature. Luis M. Molina (FTAO) Chapter 2: The blackbody spectrumQuantum and Physics the \ultraviolet 2 / 13 catastrophe" Blackbody Radiation When radiation impinges on a body, partly is absorbed and partly is reflected A black body is the one that absorbs all the radiation coming on it Independently of their composition, all blackbodies at the same temperature emit thermal radiation with the same spectrum. Figure 1. Incident radiation is Examples of black bodies: completely adsorbed after succesive Body painted in black (reflecting reflections. The radiation emitted by very little light) the hole will have a blackbody Cavity connected by a small hole spectrum to the outside Luis M. Molina (FTAO) Chapter 2: The blackbody spectrumQuantum and Physics the \ultraviolet 3 / 13 catastrophe" Backbody radiation: experimental results How do we measure the blackbody spectrum? We define the spectral radiancy RT (ν) such as RT (ν) dν is the energy emitted per unit time in the frequency interval [ν; ν + dν] from a unit area of the surface at temperature T.
    [Show full text]
  • 3. Particle-Like Properties of E&M Radiation
    3. Particle-like properties of E&M radiation 3.1. Maxwell’s equations... Maxwell (1831–1879) studied the following equationsa: ρ Gauss’s Law of Electricity: ~ E~ = ∇· ε0 Gauss’s Law of Magnetism: ~ B~ = 0 ∇· ∂B~ Faraday’s Law: ~ E~ = ∇× − ∂t ∂E~ Amp`ere-Maxwell Law: ~ B~ = µ0 J~ + ε0 ∇× ∂t ! aIn Chapter 1 these equations were given in cgs units. Here, the more conventional SI units are used. Gauss’s Law of Electricity describes how charges have associated with them, a divergent electric field E~ . Gauss’s Law of Magnetism describes the divergence of magnetic fields, B~ , and state that there is no magnetic “charge”. All magnetic charges are made up of magnetic dipoles Faraday’s Law shows how a time varying magnetic field can induce an electric field. The Amp`ere-Maxwell Law shows how a time varying electric field, as well as a current, J~, can induce a magnetic field. Elements of Nuclear Engineering and Radiological Sciences I NERS 311: Slide #1 The classical wave equation ... One of Maxwell’s greatest discoveries was that the simplest form (without time varying currents) of the last two equations, namely: ∂B~ 1 ∂E~ ~ E~ = ; ~ B~ = , (3.1) ∇× − ∂t ∇× c2 ∂t where c =1/√µ0ε0. (3.1) describes how an EM wave propagates. Time-varying electric fields induce time- varying magnetic fields that induce time-varying electric fields. and so on. The initiator can be a vertical antenna with vertical and descending swarms of electrons that give rise to axial magnetic fields that induce radial electric fields. Elements of Nuclear Engineering and Radiological Sciences I NERS 311: Slide #2 ..
    [Show full text]
  • Blackbody Radiation Is Totally Absorbed Within the Blackbody Blackbody = a Perfect Absorber A  1
    Modern physics Historical introduction to quantum mechanics Modern Physics, summer 2016 1 Historical introduction to quantum mechanics Gustav Kirchhoff (1824-1887) Surprisingly, the path to quantum mechanics begins with the work of German physicist Gustav Kirchhoff in 1859. Electron was discovered by J.J.Thomson in 1897 (neutron in 1932) The scientific community was reluctant to accept these new ideas. Thomson recalls such an incident: „I was told long afterwards by a distinguished physicist who had been present at my lecture that he thought I had been pulling their leg”. Modern Physics, summer 2016 2 Historical introduction to quantum mechanics Kirchhoff discovered that so called D-lines from the light emitted by the Sun came from the absorption of light from its interior by sodium atoms at the surface. Kirchhoff could not explain selective absorption. At that time Maxwell had not even begun to formulate his electromagnetic equations. Statistical mechanics did not exist and thermodynamics was in its infancy Modern Physics, summer 2016 3 Historical introduction to quantum mechanics • At that time it was known that heated solids (like tungsten W) and gases emit radiation. • Spectral radiancy Rλ is defined in such a way that Rλ dλ is the rate at which energy is radiated per unit area of surface for wavelengths lying in the interval λ to λ+d λ. • Total radiated energy R is called The spectral radiancy of radiancy and is defined as the tungsten (ribbon and cavity rate per unit surface area at radiator) at 2000 K. which energy is radiated into the forward hemisphere 2 R 23.5 W / cm R Rd 0 Modern Physics, summer 2016 4 Historical introduction to quantum mechanics Kirchhoff imagined a container – a cavity –whose walls were heated up so that they emitted radiation that was trapped in the container.
    [Show full text]